THE HISTORY AND SHAPE OE THE TEST-EIECE.
nealed piece. The ultimate strength falls more in every case in the annealed than it does in the natural bar. The elastic limit falls in six cases and rises to a much less extent in three. The elongation rises in five cases and falls in four. The reduction of area falls in all cases. The elastic ratio falls in five cases and rises in four.
The exceptions and irregularities are not confined to any one kind of steel, so that it is proper to average the losses and gains. The results of such condensation are given in Table XVI-J, which shows the true average of all the heats and not the average of the
TABLE XVI-J. Eound and Flat Bars in the Natural and Annealed States.
Average of all heats given la Table XVI-I Condition of bar. Shape of bar. Gain +
Bound Flat In flat.
Ultimate strength; pounds per square Inch, Natural Annealed 66079 62015 66911 69567 768 2448
Elastic limit ; pounds per square inch, Natural Annealed 46588 89683 45268 87106 1820 -2527
Elastic ratio; per cent., Natural Annealed 69.8T 68.91 68.68 62.29 1.19 1.62
Elongation in 8 inches ; percent., Natural Annealed 26.48 27.16 28.22 28.78 + 1.74 + 1.57
Reduction of area ; per cent., Natural Annealed 64.98 61.98 64.06 58.12 0.03 3.80
groups. The loss of strength from the round to the flat is much greater in the annealed than in the natural bars, and the elastic limit more than keeps pace with it. The difference can hardly be due to varying work, for the round was reduced to 2.6 per cent, of the area of the billet and the flat to 4.7 per cent., the reduction in both cases being so heavy that the results should be uniform, as far as this factor is concerned. The effect of the finishing temperature may be ignored in the annealed pieces, and yet there is a difference of 2448 pounds per square inch in ultimate strength between the flat and round.
The natural bars show less difference, which would indicate that the finishing temperature has raised the strength of the flat more than the round. This is contrary to the condition just noted that the reduction in rolling was less in the case of the flat, but it is